Heat retrieval unit for installation into a flue duct



FIG. 1 is a perspective view of a heat retrieval unit for installation into a flue duct, showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a view taken from one end thereof;

FIG. 4 is a view taken from the front of the unit;

FIG. 5 is an end view taken from the end of the unit opposite to that of FIG. 3;

FIG. 6 is a rear elevation thereof; and,

FIG. 7 is a bottom plan view thereof. 

The ornamental design for a heat retrieval unit for installation into a flue duct, as shown. 